| abstract |
The present invention includes a combination of a lithium nickel manganese composite oxide having a spinel structure represented by the following Chemical Formula 1 and a lithium nickel composite oxide represented by the following Chemical Formula 2, and has a flat section at 3.0 to 4.8 V at first charge. It provides a cathode active material and a secondary battery comprising the same. Li x M y Mn 2 - y O 4 - z z (1) Li 1 + y ' Ni z' M ' 1-z' O 2-z '' A ' z'' (2) In the above formula, 0.9 ≦ x ≦ 1.2, 0 <y <2, 0 ≦ z <0.2, and M is Al, Mg, Ni, Co, Fe, Cr, V, Ti, Cu, B, Ca, Zn, Zr, At least one element selected from the group consisting of Nb, Mo, Sr, Sb, W, Ti and Bi, and A is -1 or -divalent one or more anions; 0≤y'≤0.1, 0.5 <z'≤0.9, 0≤z ''<0.2, M 'is one or more selected from the group consisting of elements stable to six coordination such as Mn, Co, Mg, Al and A Is one or more anions of -1 or -2. |